Secret in a relationship

Me & my boyfriend have been together for one year & six months, we go through normal obstacles that any relationship has... I feel he is secretive about his phone though, whenever he goes to the bathroom he takes it & when I ask to use it to make a call he dials the number for me or will pull up the dial pad for me than give me the phone. & I even asked for his password an he said no. But I’m so open I hold no secrets. I tell him my password willingly & I leave my phone around him. An if he asks to use it I give it to him with no hesitation Because I have nothing to hide ...... should I be worried that he could be cheating ?